A critical Zookeeper bug could affect helix #3093
Description
Describe the bug and how to reproduce
The latest Helix calls zookeeper 3.6.3. Some bugs of this version can affect Helix. For example, a critical bug affects 3.6.3:
https://issues.apache.org/jira/browse/ZOOKEEPER-4712
The buggy method is org.apache.zookeeper.server.ZooKeeperServer.shutdown(boolean). This method is called by ZkServer.shutdown().
Expected behavior
Please update Zookeeper to a newer version.